verify: report first bad changeset - add linkrev and file arguments to err - track lowest reported linkrev in err - find linkrev in a couple cases - sort linkrevs when reporting a bunch of errors against a file - tidy up lots of messages - make more robust against damaged indexes - report first bad changeset if an error is encountered

#header#
    <title>#repo|escape#: tags </title>
    <description>#repo|escape# tag history</description>
    #entriesnotip%tagentry#
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